body {
    width: 100%;
    min-width: 320px;
    max-width: 640px;
    margin: 0 auto;
    font-size: 14px;
    font-family:-apple-system, Helvetica, sans-serif;
    color: #666;
    line-height: 1.5;
    height: 2000px;

}
ul  {
    margin: 0;
    padding: 0;
    list-style: none;
}
a {
    color: #666;
    text-decoration: none;
}
/* 顶部 */
.app {
    height: 45px;
}
.app ul li {
    float: left;
    height: 45px;
    line-height: 45px;
    color: #fff;
    background-color: #333;
    text-align: center;
} 
.app ul li:nth-child(1) {
    width: 8%;
}
.app ul li:nth-child(1) img {
    width: 10px;
}
.app ul li:nth-child(2) {
    width: 10%;
   
}
.app ul li:nth-child(2) img {
    width: 30px;
    vertical-align: middle;
}

.app ul li:nth-child(3) {
    width: 57%;
}
.app ul li:nth-child(4) {
    width: 25%;
    background-color: #F63515;
}
/* 搜索 */
.search-wrap {
    position: fixed;
    height: 44px;
    width: 100%;
    overflow: hidden;
    min-width: 320px;
    max-width: 640px;
}
.search-btn {
    position: absolute;
    top: 0;
    left: 0;
    height: 44px;
    width: 40px;
}
.search-btn::before {
    content: '';
    display: block;
    width: 20px;
    height: 18px;
    background: url(../images/s-btn.png) no-repeat;
    background-size: 20px 18px;
    margin: 14px 0 0 15px;

}
.search-login {
    position: absolute;
    top: 0;
    right: 0;
    height: 44px;
    width: 40px;
    color: #fff;
    line-height: 44px;

}
.search {
    position: relative;
    height: 30px;
    background-color: #fff;
    margin: 0 50px;
    margin-top: 7px;
    border-radius: 15px;
}
.jd-icon {
    position: absolute;
    left: 0;
    top: 0;
    width: 20px;
    height: 15px;
    background: url(../images/jd.png);
    background-size: 20px 15px;
    margin: 8px 8px 0 15px;
}
.jd-icon::after {
    content: '';
    display: block;
    position: absolute;
    top: 0;
    right: -8px;
    width: 1px;
    height: 15px;
    background-color: #ccc;
}
.sou {
    position: absolute;
    top: 8px;
    left: 50px;
    width: 18px;
    height: 15px;
    background-color: skyblue;
    background: url(../images/jd-sprites.png) -83px 0;
    background-size: 200px auto;
}
.slider img {
    width: 100%;
}
/* nav部分 */
nav a {
    float: left;
    width: 20%;
    text-align: center;

}
nav a img {
    width: 40px;
}
nav a span {
    display: block;
}
/* hot部分 */
.hot a{
    float: left;

}
.hot img {
    width: 100%;

}
.hot a:nth-child(1) {
    margin-top: 20px;
    width: 31%;
}
.hot a:nth-child(2) {
    width: 38%;
}
.hot a:nth-child(3) {
    margin-top: 20px;
    width: 31%;
}